Global patterns of tree density are contingent upon local determinants in the world’s natural forests

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, los autores pertenecientes a la UAM y el nombre del grupo de colaboración, si lo hubierePrevious attempts to quantify tree abundance at global scale have largely neglected the role of local competition in modulating the influence of climate and soils on tree density. Here, we evaluated whether mean tree size in the world’s natural forests alters the effect of global productivity on tree density. In doing so, we gathered a vast set of forest inventories including >3000 sampling plots from 23 well-conserved areas worldwide to encompass (as much as possible) the main forest biomes on Earth. We evidence that latitudinal productivity patterns of tree density become evident as large trees become dominant. Global estimates of tree abundance should, therefore, consider dependencies of latitudinal sources of variability on local biotic influences to avoid underestimating the number of trees on Earth and to properly evaluate the functional and social consequence

Last-century forest productivity in a managed dry-edge Scots pine population: The two sides of climate warming

Climate change in the Mediterranean, associated with warmer temperatures andmore frequent droughts, is expected to impact forest productivity and the functioning of forests ecosystems as carbon reservoirs in the region. Climate warming can positively affect forest growth by extending the growing season, whereas increasing summer drought generally reduces forest productivity and may cause growth decline, trigger dieback, hamper regenera- tion, and increase mortality. Forest management could potentially counteract such negative effects by reducing stand density and thereby competition for water. The effectiveness of such interventions, however, has so far mostly been evaluated for short time periods at the tree and stand levels, which limits our confidence regarding the efficacy of thinning interventions over longer time scales under the complex interplay between climate, stand structure, and forest management. In this study, we use a century-long historical data set to assess the effects of climate and management on forest productivity. We consider rear-edge Scots pine (Pinus syl- vestris) populations covering continental and Mediterranean conditions along an altitudinal gradient in Central Spain. We use linear mixed-effects models to disentangle the effects of alti- tude, climate, and stand volume on forest growth and ingrowth (recruitment and young trees' growth). We find that warming tends to benefit these tree populations, warmer winter temperature has a significant positive effect on both forest growth and ingrowth, and the effect is more pronounced at low elevations. However, drought conditions severely reduce growth and ingrowth, in particular when competition (stand volume) is high. We conclude that summer droughts are the main threat to Scots pine populations in the region, and that a reduction of stand volume can partially mitigate the negative impacts of more arid conditions. Mitigation and adaptation measures could therefore manage stand structure to adopt for the anticipated impacts of climate change in Mediterranean forest ecosystems.Ministerio de Economía y Competitivida

Design of a fingerprint, biometric identification system using capacitive sensors

RESUMEN: El sistema de reconocimiento biométrico está basado en el procesamiento digital de una imagen de una huella dactilar de 256 x 300 píxeles, la cual se toma por medio de un sensor capacitivo, y luego se transmite a un computador (PC) por medio de una interfaz de comunicación. En este trabajo se presenta el diseño de un sistema donde se configura el sensor y se obtiene la imagen para comunicarla al PC. El procesamiento de la huella por medio de algoritmos de filtrado de imágenes propios; el primero de los filtros resalta los valles y crestas de la huella, y se aplica a la imagen por regiones, el siguiente algoritmo se encarga de filtrar la imagen para extraer las características más importantes, luego se lleva la imagen a sólo dos niveles de gris, las crestas a un ancho de un solo píxel (esqueletización), y por último el reconocimiento, se hace hallando la ubicación de las características o minucias de cada huella y las distancias entre ellas, generando vectores de información.ABSTRACT: A fingerprint, biometric recognition system was designed. The system is based on the digital processing of fingerprints of 256 x 300 pixels, which are recorded by a capacitive sensor and then transmitted to a PC by means of a communication interface. Successive steps of configuring the sensor, obtaining the image, and communicating with the PC were conducted. Image processing is performed by the PC using own digital image filtrate algorithms. The first level of filtering stresses the valleys and crests of the fingerprint; the image is devided in regions for applying this algorithm. The next algorithm filters the image to extract the most relevant characteristics. Subsequently, the image is converted to only two levels of gray, and the crests are converted to one-pixel width (skeleton). Finally, recognition is done by seeking the location of the relevant characteristics of each fingerprint and determining the distances between them, generating information vectors

Evaluating tree-to-tree competition during stand development in a relict Scots pine forest: how much does climate matter?

Key message: Competitive interactions change over time and their influence on tree growth is intensified during drought events in marginal Scots pine populations. Abstract: Competition is a key factor driving forest dynamics and stand structure during the course of stand development. Although the role neighbourhood competition on stand dynamics has received increasing attention, the response of competition to environmental fluctuations and stand development remains poorly explored. We evaluated changes in competition during stand development in a dry-edge Scots pine relict population located in Central Spain. Typically, tree-to-tree interactions have been investigated through static competition measurements, which usually lack the temporal variation associated to natural forest development and environmental conditions. Here, we assessed how individual and neighbourhood components of competition evolved along a 35-year period, and we related competition dynamics to population structure and drought levels. On six plots, 508 trees were mapped and diameters at breast height (DBH) were measured. Two increment cores were taken from target trees to derive basal area increment (BAI), and neighbourhood was reconstructed back to 1980. Results provide insights into inter-annual variability in competition effects and their role on tree radial growth depending on climatic conditions. From the year 2005 onwards, both individual and neighbourhood components of competition showed a decoupled pattern over time. This effect was particularly pronounced during the extreme drought in 2012, in which the individual component decreased, whereas the neighbourhood component increased. In addition, climatic variability modulated the competition effects during stand development. This approach of evaluating competition dynamics proves to be promising for studying forest stand development and the influence of climate impacts on tree populations subjected to xeric conditions

In vivo extracellular matrix protein expression by human periodontal ligament after stimulation with orthodontic force

It is well known that the orthodontic force applied to teeth generates a series of events that remodel the periodontal ligament (PDL). Extracellular matrix proteins (ECM) are described as molecular regulators of these events. However, the exact contribution of these proteins in human PDL modeling by orthodontic force application in vivo is not known. The aim of this present study was to evaluate the protein expression of fibronectin, laminin and vitronectin by human PDL from teeth on which orthodontic force was applied. Twenty healthy individuals were included in the study. PDL was obtained from teeth after a 3-week treatment with orthodontic force. PDL-protein samples were separated on 7.5% SDS-PAGE Western blot analysis with specific monoclonal antibodies for fibronectin, laminin and vitronectin. Bands were visualized with an enhanced chemiluminescence detection system and densitometric. Scanning of bands was carried out to compare differences in protein expression. A significant increment in fibronectin (13.9%), laminin (16.5%) and vitronectin (14.2%) expression was found in PDL from teeth treated with orthodontic force for 3 weeks in comparison with teeth in the control group. Our results support the concept that molecular changes take place by application of orthodontic forces to the PDL. Over expression of these proteins suggests that extracellular matrix (ECM) remodeling could be generated in response to mechanical stress.Keywords: Extracellular matrix proteins, periodontal ligament, orthodontic forceAfrican Journal of Biotechnology Vol. 9(34), pp. 5599-5604, 23 August, 201

Reproductive phenology determines the linkages between radial growth, fruit production and climate in four Mediterranean tree species

The influence of climate on seed or fruit production and tree growth is a central question in forest ecology, with a key role on forest dynamics. However, the mechanisms linking inter- and intra-annual climate variability, fruiting and growth remain poorly understood, although they seem to be largely species-specific. The resource-matching hypothesis posits that fruit production responds to annual environmental variability, predicting a positive relationship between reproduction and growth, whereas other hypotheses such as resource switching or resource budget imply allocation trade-offs between reproduction and growth. Climate control over fruiting is thought to be more likely in variable, limiting environments such as those existing in seasonally dry Mediterranean forests. However, the studies about these forests are much scarcer than on temperate ecosystems, probably due to the sparseness and shortness of fruit production records. Here we analysed the relationships between monthly climate variables, tree-ring widths and fruit production at stand level in four tree species under different climatic conditions in Spain (12-27 trees and 24-54 radii were sampled in each site). For the species from xeric sites such as Pinus pinea, Castanea sativa and Quercus ilex, tree-ring width positively correlated with fruit production, as envisaged by the resource-matching hypothesis. This association was driven by prior wet winter climate conditions, which enhanced growth. Some of the significant correlations between climate variables and fruit yield corresponded to key reproductive phenophases. On the other hand, for the species from mesic sites (Abies alba) no positive growth–fruit production correlation was found, likely due to the mismatch in the effect of climatic factors on growth and fruiting. These results support the hypothesis that climatic conditions, particularly a positive water balance, play a major role as a proximate cause of fruit production in seasonally dry Mediterranean forests and underscore the importance of species-specific reproductive phenology traitsPublishe

Forest productivity in southwestern Europe controlled by coupled North Atlantic and Atlantic Multidecadal Oscillations

The North Atlantic Oscillation (NAO) depicts annual and decadal oscillatory modes ofvariability responsible for dry spells over the European continent. The NAO therefore holds agreat potential to evaluate the role, as carbon sinks, of water-limited forests under climatechange. However, uncertainties related to inconsistent responses of long-term forestproductivity to NAO have so far hampered firm conclusions on its impacts. We hypothesizethat, in part, such inconsistencies might have their origin in periodical sea surfacetemperature anomalies in the Atlantic Ocean (i.e., Atlantic Multidecadal Oscillation, AMO).Here we show strong empirical evidence in support of this hypothesis using 120 years ofperiodical inventory data from Iberian pine forests. Our results point to AMO+ NAO+ andAMO−NAO− phases as being critical for forest productivity, likely due to decreased winterwater balance and abnormally low winter temperatures, respectively. Our findings could beessential for the evaluation of ecosystem functioning vulnerabilities associated with increasedclimatic anomalies under unprecedented warming conditions in the Mediterranean